1. Field
The invention is in a specialized field of equipment for medical use, specifically tracheal tubes as used for conducting gases or vapors along the trachea, as for example by anesthesiologists in the administration of anesthesia to patients undergoing surgery.
2. State of the Art
Since the first reported use of a straight tracheal tube for the administration of anesthesia in the year 1889, such tubes have been designed with various shapes and curvatures and have been made either rigid or flexible. Flexible tubes automatically conform in shape and curvature to body requirements in individual instances, but have proven dangerous in that kinking has occurred and has resulted in critical stoppages in flow. A non-kinking, preformed, flexible tube of L-shape, a so-called "Oxford Tube ", having a widely curved, right-angle bend adapted for placement in the trachea and posterior pharynx, is known, and a similar tube having a sigmoid curvature for similar placement in the trachea and posterior pharynx is proposed by Kuhn in his U.S. Pat. No. 3,363,629. Neither of these tracheal tubes are entirely satisfactory. In most tracheal tubes presently used, a port -- a so-called "Murphy eye" -- is provided in one side of the distal end portion of the tube as a safety measure against accidental advancement of the tube onto the carina at the lower end of the trachea.